Despite conceptual breakthroughs in dual photoredox- and nickel-catalyzed arylation of radicals, the approach remains largely limited to localized C-centered radicals. Here, we extend it to allylic radicals, focusing on -allyl heterocycles. Using [Ir(dF(CF)ppy)(dtbbpy)]PF and NiCl(dtbbpy) under visible light, we achieve regioselective γ-amino radical arylation, yielding enamines in good yields. In some cases, in situ photoisomerization produces the isomer, influenced by the substrate and the triplet state energy of the photocatalyst.
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http://dx.doi.org/10.1021/acs.joc.4c01912 | DOI Listing |
Sci Bull (Beijing)
December 2024
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China. Electronic address:
Divergent synthesis of valuable molecules through common starting materials and metal catalysis represents a longstanding challenge and a significant research goal. We here describe chemodivergent, highly enantio- and regioselective nickel-catalyzed reductive and dehydrogenative coupling reactions of alkynes, aldehydes, and silanes. A single chiral Ni-based catalyst is leveraged to directly prepare three distinct enantioenriched products (silyl-protected trisubstituted chiral allylic alcohols, oxasilacyclopentenes, and silicon-stereogenic oxasilacyclopentenes) in a single chemical operation.
View Article and Find Full Text PDFNat Commun
December 2024
Key Laboratory of Precision and Intelligent Chemistry and Department of Chemistry, University of Science and Technology of China, 230026, Hefei, P. R. China.
Even though tuning electronic effect of chiral ligands has proven to be a promising method for designing efficient catalysts, the potential to achieve highly selective reactions by this strategy remains largely unexplored. Here, we report a palladium-catalyzed enantioselective ring-closing aminoalkylative amination of aminoenynes enabled by rationally tuning the remote electronic property of 1,1'-binaphthol-derived phosphoramidites. With a tailored 6,6'-CN-substituted 1,1'-binaphthol-derived phosphoramidite as a ligand, a broad range of aromatic amines are compatible with this reaction, allowing the efficient synthesis of a series of enantioenriched exocyclic allenylamines bearing saturated N-heterocycles with up to >99% enantiomeric excess.
View Article and Find Full Text PDFJ Org Chem
December 2024
College of Chemical & Pharmaceutical Engineering, Hebei Province Key Laboratory of Molecular Chemistry for Drug, Hebei University of Science & Technology, Shijiazhuang 050018, China.
We report herein that three facile rearrangements of epoxy ketones can be employed for the efficient and practical synthesis of cephalotaxine, the parent member of the family of alkaloids. The Meinwald rearrangement of epoxy ketone (90%) was used for the preparation of the dense functional groups in the cyclopentane ring of cephalotaxine. A novel acid-catalyzed umpolung S2' rearrangement and the Wharton transposition reaction of epoxy ketones were also developed to synthesize the Mori intermediate via the key azaspiro allylic alcohols in a stereodivergent manner.
View Article and Find Full Text PDFChem Sci
December 2024
Department of Chemistry, Indian Institute of Technology Madras Chennai 600036 India
An intermolecular carboamination reaction of allyl amines under Pd(ii)-catalysis is reported, expediting the synthesis of valuable vicinal diamines embedded in a functionally enriched linear carbon framework with high yields and exclusive Markovnikov selectivity. Central to our approach is the strategic use of a removable picolinamide auxiliary, which directs the regioselectivity during aminopalladation and stabilizes the crucial 5,5-palladacycle intermediate. This stabilization facilitates oxidative addition to carbon electrophiles, enabling the simultaneous incorporation of diverse aryl/styryl groups as well as important amine motifs, such as sulfoximines and anilines, across carbon-carbon double bonds.
View Article and Find Full Text PDFJACS Au
November 2024
Schulich Faculty of Chemistry and the Resnick Sustainability Center for Catalysis, Technion - Israel Institute of Technology, Technion City, Haifa 3200008, Israel.
With growing efforts pushing toward sustainable catalysis, using earth-abundant metals has become increasingly important. Here, we present the first examples of cobalt PCP pincer complexes that demonstrate dual stereoselectivity for allyl ether isomerization. While the cationic cobalt complex [((PCP)Co)-μ-N][BAr ] () mainly favors the -isomer of the enol ether, the corresponding methyl complex [(PCP)CoMe] () mostly gives the -isomer.
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